Hi,
I would suggest you use a column to create a list of names marked as yes.
Let's say we use column H for this, select cells H1 to H100, copy the following formula and press Control-Shift-Enter.
=IFERROR(INDEX($C:$C,SMALL(IF($F:$F="Yes",ROW($F:$F),""),ROW())),"")
Now, when you create the Data Validation list, enter the following formula into the Source:
=INDIRECT("H1:H"&100-COUNTIF(H1:H100,""))
Regards,
Zach